Electrical signaling system



June 17, 1930.

ELECTRICAL S IGNALING SYSTEM Filed Dec. 12, 1924 J. BETHENOD mm-unlu lllllllmllF INVENTOR 3%Q (QZ/CQL TTORNEY Patented June 17, 1930 UNEE ETATES JOSEPH BETHENOID,

OF PARIS, FRANCE ELECTRICAL SIGNALING SYSTEM Application filed December 12, 1924, Serial My invention relates to electrical signaling systems and particularly to radio signaling systems in which the frequencies of the received waves are successively reduced by means of modulation. My invention also relates to signaling methods.

One of the principal objects of my invention is the provision of electrical systems in which the frequency of the received waves is successively reduced by modulation of the received waves.

Another principal object of my invention is the provision of inexpensive and simplified apparatus capable of employment with systems functioning on long waves for enabling said systems to effectively and etficiently function on comparatively short waves.

Other objects and advantages of my invention will be apparent from the following description taken in connection with the accompanying drawing in which:

The single figure is a schematic diagram of one of the preferred embodiment-s of my invention.

The new methods forming a part of the subject-matter of the present invention consist in the application, for gradual or stepwise decreasing of the frequencies of the received waves, of devices of the type described in French Patent No. 511,244. The

received waves of said frequency F are modulated to a lower frequency f of any desired value by means of one or more stages of modulation. The modulation of the received waves at frequency 1'' may be accomplished by various methods, especially for example: by those disclosed in the above cited French patent, and more particularly by Figure 3 and the descriptive matter relating thereto.

Referring to the single figure, the antenna circuit comprises, an antenna 1, a variable antenna tuning condenser 2, a primary winding 3, all connected in series and grounded as shown.

The grid-filament circuit of triode 6 comprises, secondary winding 4:, inductively coupled to the winding 3 and a grid biasing battery 7 connected in seriesas shown. A

variable tuning condenser 5 is connected No. 755,371, and. in France April 14, 1924.

across the secondary winding for appropriately tuning the said circuit to the incoming waves.

The plate filament circuit of triode 6 comprises, a plate battery primary coil 8 and a coupling coil 10 all connected in series across the plate and filament as shown. The variable condenser 9 may be connected across coil 8 for appropriately tuning the platefilament circuit of triode 6. A source or" modulating frequency M is inductively coupled to the plate-filament circuit of triode 6 by means of coils 10 and 11. This source of modulating frequency could also be connected in various other parts of the system as for example in the grid filament circuit. The coil 10 may be shunted by a. condenser if desired.

The grid-filament circuit of detecting triode 17 comprises a grid condenser 18 with a grid leak resistance in shunt therewith and a secondary coil 15 all connected in series across the grid and filament as shown. A variable condenser 16 is connected across the secondary coil 15 for appropriately tuning the grid-filament circuit.

The coils 8 and 15 are coupled together by means of an intermediate loop circuit comprising coils 12 and 13 and variable condenser 14 all connected in series. The coil 8 is inductively coupled to the coil 12 and the coil 13.is inductively coupled to the coil 15.

The plate-filament circuit of triode 17 comprises a plate battery and a primary coil 19 all connected in series across the grid and filament as shown. A variable condenser 20 is connected across the coil 19 for appropriately tuning the plate-filament circuit and the coil 21 is inductively coupled to coil 19 for energizing the signal responsive device or another stage of modulation etc.

The system as described above functions as follows: Assume waves of frequency F impinge on the antenna 1. The antenna circuit and the grid filament circuit of triode 6 are appropriatelytuned to this frequency by variable condensers 2 and 5 respectively. The oscillations in the plate-filament circuit of triode 6 are modulated by frequency f by means of the coils and 11 and a source M of modulating frequency. This modulating frequency is detected by the detecting triode 17, the plate-filament circuit of the said triode being tuned to the frequency f by means of the condenser 20. The oscillations of frequency f maybe modulated to lower frequencies by means of one or more other stages of modulation connected tothe coils 21.

During the non-reception of waves, the loop circuit comprising coils 12 and 13 and variable condenser 14 being tuned to the signal waves of frequency F, prevents any appreciabletransfer of energy at frequency f to detector triode 17. The coil 21 may also be connected to existing apparatus adapted to function more efficiently on comparatively short Wave lengths. The apparatus as shown by the single figure when added to existing stations arranged to function on comparatively long wave lengths, viz, from 150 to 8000 meters, will enable said systems to effectively and efliciently function on comparatively short wave lengths, viz, in the neighborhood of 100 meters.

An appropriate coupling may be established between the grid-filament and the plate-filament circuits of one of the triodes or between the said circuits of all of the said triodes to thereby effect regeneration.

Attention is called to the fact that the system as shown by the figure is substantially similar to a complete radio telephone transmitting station, the devices 1 to 14 constituting the transmitting station; while the devices 14 to 20 inclusively, constitute the receiving equipment. In this arrangement the triode 6 is the high frequency generator, with separate excitation furnished by the elements 1 to 5 inclusive and is coupled by means of coils 8 and 12 with the transmitting aerial formed by the tuned circuit 121814. In this case the outgoing waves are modulated at frequency f by the elements 10 and 11.

The intermediate loop circuit 1213-14 is not indispensable if the circuit 1516 is of sufficiently low damping. In this case the coil 8 is directly coupled to the coil 15. The intermediate circuit 1213-14 may be replaced if desired by an electrical filter.

While I have shown and described various preferred embodiments of my invention 1' not limit myself to the same but may employ such other modifications as come within the spirit and scope of my invention.

Claims:

1. In a radio signaling system the combination of an antenna circuit, a space dis charge device having a grid circuit and a plate circuit,'said grid circuit being coupled to the antenna circuit and tuned to the frequency thereof, an auxiliary source of electrical oscillations of super-audible frequency coupled to the plate circuit of said space discharge device, a circuit tuned to the fre quency of said antenna circuit coupled to the plate circuit of said space discharge device, and a second space discharge device coupled to said last mentioned tuned circuit and arranged to detect the current flowing in said tuned circuit, the plate circuit of said second space discharge device being tuned to the frequency of said auxiliary source of oscillations of super-audible frequency.

2. In a radio signaling system the combination of an antenna circuit tuned to a first frequency, a space discharge device having grid and plate circuits, said grid circuit being coupled to said antenna circuit and tuned to said first frequency, an auxiliary source of electrical oscillations of a superaudible frequency coupled to the plate circuit of said space discharge device, and a space discharge device detector coupled to said space discharge device, the plate circuit of said detector being tuned to said superaudible frequency.

8. In a radio signaling system the combination of an antenna circuit tuned to a first frequency, a space discharge device having grid and plate circuits, said grid circuit being coupled to said antenna circuit, an auxiliary source of oscillations having a super-audible frequency materially different from said first frequency, said source being coupled to the plate circuit of said space discharge device, and a space discharge device detector having grid and plate circuits, said grid circuit being coupled to said triode, the grid circuit of said detector being tuned to said first mentioned frequency and being adapted to reproduce in its plate circuit electrical oscillations of the frequency equal to the frequency of said auxiliary source.

4. In a radio signaling system the combination of an antenna circuit, a space dis charge device having an input and an output circuit, said input circuit being coupled to said antenna circuit, and an auxiliary source of electrical super-audible oscillations coupled to the output circuit of said space discharge device and arranged to modulate the output of said space discharge device at a quency of the received electrical oscillations, and a detector having a grid and a plate circuit, said grid circuit being coupled to said space discharge device, the plate circuit of said detector being tuned to the frequency of said auxiliary source.

5. The method of signaling which comprises receiving a radio frequency carrier current, amplifying said carrier current, varying the amplitude of said carrier current at a super-audible modulation frequency at the point of reception without substantially changing the frequency of said carrier current, whereby to produce a modulated n: 7 frequency substantially lower than the fred carrier wave, detecting said modulated carrier wave whereby to produce a modulating super-audible frequency, and filtering said modulating frequency from said radio frequency carrier current.

6. The method of signaling which comprises receiving a radio frequency carrier current, varying the amplitude of said carrier current at the point of reception, said variations being carried out at a superaudible modulation frequency, whereby to produce a modulated carrier wave filtering said modulation frequency from said modulated wave and detecting said last mentioned wave.

JOSEPH BETI-IENOD. 

